This invention relates to a temperature measuring device, and more particularly, to an improved temperature measuring device employing a sensor which is exposed to an environment such as ambient air or to an object to be measured and which generates an electric signal representing the temperature of the environment or object. A temperature measuring device employing a thermistor which generates electric signals in proportion to temperature of an object is well known. Such a device is relatively inaccurate because the temperature characteristic of the thermistor is nonlinear and the thermistor itself cannot provide an accurate output signal over a wide temperature range.
It is, therefore, a primary object of this invention to provide an accurate temperature measuring device which measures the temperature of a semiconductor photoelectric transducer itself in accordance with the principle that the photoelectric conversion efficiency of the transducer varies with temperature and that the temperature coefficient of the photoelectric conversion efficiency varies with the wavelength or the spectrum component of received light from a light source. The photoelectric transducer can be placed to be affected by ambient temperature or temperature of an object and thus act as a temperature measuring device.
It is a further object of this invention to provide a temperature measuring device which generates output signals representing temperature corresponding to ratios based on the outputs generated from a semiconductor photoelectric transducer for different wavelength regions.
It is still another object of this invention to provide a temperature measuring device which employs a light emitting means for emitting light to the transducer, the spectrums of which are constant with respect to time.
According to this invention, there is provided a semiconductor photoelectric transducer which operates in response to a particular wavelength or a particular spectrum component of light received by the transducer so that its outputs are free from the undesirable effect caused by the fact that the temperature coefficient of the photoelectric conversion efficiency varies with the wavelength or the spectrum component of received light. Therefore, output signals representing temperature can be obtained by placing the semiconductor photoelectric transducer in a temperature measuring environment and computing the ratio based on the outputs generated from the semiconductor photoelectric transducer. Furthermore, when employing the semiconductor photoelectric transducer as a light receiving element in optical measuring, a temperature compensation value can be obtained from its outputs, thus considerably improving the measuring accuracy.